The goals of this Program are to define the organization and expression of identified genetic loci which function as essential components of cell growth and development. Two criteria are critical to a productive study of growth and developmental regulation. The organism of choice must be amenable to both genetic and biochemical manipulation, and in each case specific genetic loci must be identified which play a key role in the process being studied. (a) The cell membrane has an essential role in the coordination of cellular events in such diverse organisms as Caulobacter, yeast, E. coli and Dictyostelium. L. Shapiro and S. Henry will determine the mechanism by which membrane lipid and protein synthesis is involved in the temporal and spacial regulation of a set of identified structural proteins during the Caulobacter cell cycle. (b) S. Henry will analyze the structure and expression of the gene encoding the essential lipid-biosynthetic enzyme inositol-l-phosphate synthase during the yeast cell cycle, in order to understand the coordinate control of cytoplasmic and membrane-bound enzymes. (c) Chromosomal genetic loci in E. coli have been shown to encode proteins which participate in a variety of membrane-associated functions. P. Silverman will determine how the cell envelope functions in what appears to be an organizational capacity to regulate donor activity and the ilv biosynthetic pathway. (d) Motility mutants in Dictyostelium express a surprising array of membrane-mediated functions which are related to the cytoplasmic actin-myosin complex. Dr. Clarke will determine how such events as motility, axenic growth, pinocytosis, cell shape and surface substrate-cell interactions are co-regulated by the products of single genetic loci. (e) Drs. J. Chase and S. Hawley are studying DNA ligase, which is an essential enzyme in replication, repair and recombination, from an organism, Drosophila, which exhibits a full complement of developmental functions yet permits access to genetic manipulation. Their objectives are to determine how the gene encoding histone proteins form a multigene family whose expression varies as a function of cell differentiation. The goals of Drs. Emmons and Childs are to determine the consequences of this differential gene expression and to understand the organization and controlled expression of this multigene family in C. elegans.